MEMS microphone modules and wafer-level techniques for fabricating the same

ABSTRACT

The disclosure describes various MEMS microphone modules that have a small footprint and can be integrated, for example, into consumer electronic or other devices in which space is at premium. Wafer-level fabrication techniques for making the modules also are described.

This disclosure relates to MEMS microphone modules and wafer-levelfabrication techniques.

A microphone refers to a transducer or sensor that converts sound intoelectrical signals. One type of microphone that can be integrated intosmall electronic devices is fabricated as a micro-electromechanicalsystem (MEMS) and sometimes is referred to as a MEMS microphone or aMEMS condenser microphone. Such microphones can provide superior soundquality and demonstrate greater heat tolerance than some other types ofmicrophones, which facilitates the use of high-volume surface mountmanufacturing techniques. MEMS microphones currently are incorporatedinto a wide range of consumer electronic and other products such ascellphones, laptops, headsets and media tablets, as well as gamingapplications, cameras, televisions and hearing aids. In some cases,multiple microphones may be incorporated into a single electronicproduct. For example, multiple microphones are now being adopted in somesmartphones for noise suppression, in which the cancellation of ambientsounds is important for handsets when carrying out voice commands.Likewise, some laptops have three microphones: two are used in the lidon each side of a Webcam to provide clear, noise free communication, anda third is used to suppress the noise from the keys on the keyboard.

In view of the increasingly widespread use of MEMS microphones invarious electronic devices, it is desirable to find ways to improvemanufacturing efficiency, reduce costs and reduce the size of the MEMSmicrophones.

SUMMARY

The present disclosure describes MEMS microphone modules and fabricationtechniques that, at least in some implementations, address some or allof the foregoing issues.

For example, the disclosure describes various wafer-level fabricationtechniques. A particular wafer-level method of fabricating multiple MEMSmicrophone modules includes providing a substrate wafer on which aremounted pairs of devices, each pair including a MEMS microphone deviceand an integrated circuit device to perform processing of signals fromthe MEMS microphone device. A cover wafer is provided over the substratewafer to form a wafer stack, where the cover wafer and substrate waferare separated by a spacer that serves as a wall surrounding respectivepairs of devices. The method includes dividing the wafers intoindividual MEMS microphone modules each of which includes at least oneof the MEMS microphone devices and an associated one of the integratedcircuit devices, and wherein each MEMS microphone module has an openingthrough which sound can enter the MEMS microphone module. The disclosuredescribes other wafer-level fabrication techniques as well.

The disclosure also describes various MEMS microphone modules. Forexample, in one aspect, a MEMS microphone module includes a firstsubstrate and a second substrate on which is mounted a MEMS microphonedevice. The second substrate is separated from the first substrate by afirst spacer. An integrated circuit device is mounted on the firstsubstrate and arranged to perform processing of signals from the MEMSmicrophone device. A cover is separated from the second substrate by asecond spacer. The module has an opening in the cover or in the secondspacer through which sound can enter.

According to another aspect, a MEMS microphone module includes asubstrate, a MEMS microphone device mounted on a first surface of thesubstrate, and an integrated circuit device mounted on a second surfaceof the substrate, where the second surface is on an opposite side of thesubstrate from the first surface, and the integrated circuit device isarranged to perform processing of signals from the MEMS microphonedevice. A cover is separated from the substrate by a first spacer, and asecond spacer is on the second surface of the substrate. The module hasan opening in the cover or in the first spacer through which sound canenter.

Some implementations include acoustics-enhancing features on an innersurface of the second spacer or an inner surface of the cover. Theacoustics-enhancing features can be composed, for example, of a polymermaterial, a foam material or a porous material. Some implementationsinclude one or more projections extending from an exterior surface ofthe cover. The projections can be used, for example, to facilitatepositioning of the MEMS microphone module within a housing of anelectronic or other device.

One or more of the following advantages are provided in someimplementations. For example, the MEMS microphone modules can, in somecases, improve reliability, performance or ease of manufacturing. Themodules can be made to have a compact size with a relatively smallfootprint, which can be important for applications in which space is ata premium. Furthermore, the modules can be fabricated in wafer-levelprocesses, which can facilitate the manufacture of multiple modules.

Other aspects, features and advantages will be readily apparent from thefollowing detailed description, the accompanying drawings and theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross-section of an example of a MEMS microphonemodule.

FIGS. 2-4 illustrate steps in an example wafer-level fabricationprocess.

FIG. 5 illustrates another example of a MEMS microphone module.

FIG. 6 illustrates yet another example of a MEMS microphone module.

FIGS. 7, 8 and 9 illustrates further examples of MEMS microphonemodules.

FIG. 10 illustrates an example of a MEMS microphone module combined witha flash module.

FIGS. 11-15 illustrate steps in an example wafer-level fabricationprocess.

FIG. 16 illustrates another example of a wafer-level fabricationprocess.

FIG. 17 illustrates a further example of wafer-level fabricationprocess.

FIG. 18 illustrates a wafer stack resulting from the process of FIG. 17.

FIG. 19 is an example of a MEMS microphone module obtained afterseparating the stack of FIG. 18.

DETAILED DESCRIPTION

As shown in FIG. 1, a MEMS microphone module 20 includes an integratedcircuit (IC) 22 and a MEMS device 24 mounted on a printed circuit board(PCB) substrate 26. Electrical wires 27 or electrical pads on theunderside of IC 22 and MEMS device 24 can provide connections to PCBsubstrate 26. IC 22 can be implemented, for example, as a semiconductorchip device and can include circuitry that performs analog-to-digitalprocessing of signals from MEMS device 24. The module 20 includes acover 28 that includes an opening 30 to allow sound to enter the module.Cover 28 can be composed, for example, of a glass material, a plasticmaterial or a printed circuit board (PCB) material such as FR4, which isa grade designation assigned to glass-reinforced epoxy laminatematerial. PCB substrate 26 and cover 28 are separated by spacers 32 thatform sidewalls for the module. Spacers 32 may be formed as a singleintegral wall that surrounds MEMS microphone device 24 and IC 22.

Electrical contacts such as solder balls 29 or contact pads can beprovided on the outer, bottom surface of PCB substrate 26. Conductivevias 31 can provide electrical connections from wiring 27 to solderballs 29. Module 20 can be mounted, for example, on a printed circuitboard, e.g., using surface mount technology (SMT), next to otherelectronic components. The printed circuit board can be a constituent ofan electronic device (e.g., a hand-held communication device such as acellphone or smartphone), a laptop, a headset, a media tablet, anelectronic product for a gaming application, a camera, a television or ahearing aid. Spacers 32 and cover 28 can be coated or lined with aconductive material to provide electromagnetic shielding.

Module 20 can be made relatively small. For example, in someimplementations, module 20 has dimensions on the order of about 5 mm ofless (width)×5 mm or less (length)×3 or less mm (height). For example,in a particular implementation, module 20 has dimensions on the order ofabout 3 mm (width)×3 mm (length)×1 mm (height). Different dimensions maybe appropriate for other implementations.

Multiple MEMS microphone modules 20 can be fabricated at the same time,for example, in a wafer-level process. Generally, a wafer refers to asubstantially disk- or plate-like shaped item, its extension in onedirection (z-direction or vertical direction) is small with respect toits extension in the other two directions (x- and y-directions orlateral directions). On a (non-blank) wafer, a plurality of similarstructures or items can be arranged, or provided therein, for example,on a rectangular grid. A wafer can have openings or holes, and in somecases a wafer may be free of material in a predominant portion of itslateral area. In some implementations, the diameter of a wafer isbetween 5 cm and 40 cm, and can be, for example between 10 cm and 31 cm.The wafer may be cylindrical with a diameter, for example, of 2, 4, 6, 8or 12 inches, one inch being about 2.54 cm. The wafer thickness can be,for example, between 0.2 mm and 10 mm, and in some cases, is between 0.4mm and 6 mm.

In some implementations of a wafer-level process, there can beprovisions for at least ten modules 20 in each lateral direction, and insome cases at least thirty or even fifty or more modules in each lateraldirection. Examples of the dimensions of each of the wafers are:laterally at least 5 cm or 10 cm, and up to 30 cm or 40 cm or even 50cm; and vertically (measured with no components arranged thereon) atleast 0.2 mm or 0.4 mm or even 1 mm, and up to 6 mm or 10 mm or even 20mm.

FIGS. 2-4 illustrate various steps in an example wafer-level fabricationprocess. As shown in FIG. 2, multiple ICs 22 and MEMS devices 24 aremounted on a PCB substrate wafer 40, for example, by pick-and-placeequipment. Pairs of ICs 22 and MEMS devise 24 are spaced from oneanother in view of the lateral dimensions of modules. PCB substratewafer 40 can comprise standard PCB materials (e.g., fiber glass orceramic). Solder balls 29 can be provided on the side opposite the sideon which ICs 22 and MEMS devise 24 are mounted. Conductive vias 31 canbe provided through PCB substrate wafer 40 for electrical connectionbetween wires 27 and the solder balls 29 on the exterior surface of thePCB substrate wafer.

Next, as illustrated in FIG. 3, spacers 42 are formed, for example, by areplication or vacuum injection technique. The spacers 42 can bereplicated, for example, directly on PCB substrate wafer 40 (or on acover wafer 46, described below) by a vacuum injection technique. Insome implementations, spacers 42 are composed of a polymer material, forexample, a hardenable (e.g., curable) polymer material, such as an epoxyresin. In other implementations, spacers 42 are made of a PCB material(e.g., fiber glass or ceramic). In some implementations, instead ofusing a direct replication by a vacuum injection technique to formspacers 42, a pre-formed spacer wafer is attached to PCB substrate wafer40. The pre-formed spacer wafer can be formed, for example, byreplication. The spacer wafer can include openings (i.e., through-holes)44 such that, when the wafers are stacked on one another, ICs 22 andMEMS devices 24 are laterally encircled by sidewalls formed by thespacer wafer. In case of a PCB spacer wafer, openings 44 can be made,for example, by micromachining.

As illustrated in FIG. 4, cover wafer 46 is attached over spacers 42.Cover wafer 46 includes openings 48 which correspond to the opening 30in FIG. 1. Openings 48 can be formed, for example, by micromachining orby a replication technique. Openings 48 may have a circular, square orother shape. The shape and size of openings 48 can be selected toachieve desired acoustics or sound propagation.

If a spacer wafer is used to provide spacers 42, then the wafers (i.e.,PCB substrate wafer 40, spacer wafer and cover wafer 46) can be attachedto one another, for example, by glue or some other adhesive to form astack 49. In some implementations, the wafers can be attached to oneanother in a different order than the one described above. For example,cover wafer 46 can be attached to the spacer wafer to form a sub-stack,which subsequently is attached to PCB substrate wafer 40. As also notedabove, in some implementations, spacers 42 are formed by a replicationor vacuum injection technique, and may be formed directly on PCBsubstrate wafer 40 or cover wafer 46.

After stack 49 is formed, it is separated, for example, by dicing alongimaginary lines 50 (see FIG. 4) into multiple individual modules 20,each of which includes an IC 22 and associated MEMS microphone 24, asshown in FIG. 1. If desired, the exterior surfaces of sidewalls 32 andcover 28 can be coated (or lined) with a conductive material to provideelectromagnetic shielding of the components within module 20.

The footprint (i.e., the area coverage) of module 20 is dictated, atleast in part, by the combined footprints of IC 22 and MEMS device 24.FIGS. 5 and 6 illustrate examples of modules in which IC 22 and MEMSdevice 24 are disposed one over the other, rather than side-by-side. Insome implementations, such arrangements can help reduce the overallfootprint of the module.

For example, FIG. 5 shows an example of a module 58 in which IC 22 andMEMS device 24 are mounted on different PCB substrates 60, 62. In thisexample, the first PCB substrate 60, on which MEMS device 24 is mounted,is disposed between cover 28 and the second PCB substrate 62 (on whichIC 22 is mounted). First spacers 32 separate cover 28 and first PCBsubstrate 60, and second spacers 64 separate first PCB substrate andsecond PCB substrate 62. Electrical connections 68 can extend fromwiring 66 through first PCB substrate 60, through spacers 64 and throughsecond PCB substrate 62 to provide electrical access to MEMS device 24from outside module 58. Likewise, an electrical connection 70 can extendfrom wiring 67 through PCB substrate 62 to provide electrical access toIC 22 from outside module 58.

FIG. 6 illustrates an example of a module 76 in which both IC 22 andMEMS device 24 are mounted on opposite sides of the same PCB substrate72. In the illustrated example, MEMS device 24 is mounted on surface 78,which is closer to cover 28, whereas IC 22 is mounted on the oppositeside on surface 80. First spacers 32 separate cover 28 and PCB substrate72 from one another, and second spacers 74 are attached to other side ofPCB substrate 72. Electrical connections 82 can extend from wiring 66through PCB substrate 72 and through spacers 74 to provide electricalaccess to MEMS device 24 from outside module 76. Likewise, electricalconnections 84 can extend from wiring 67 through PCB substrate 72 andthrough spacers 74 to provide electrical access to IC 22 from outsidemodule 76.

As illustrated in the example of FIGS. 5 and 6, portions of theelectrical connections are embedded within spacer walls 64, 74. If a PCBspacer wafer is used to provide spacers 64, 74, then electricalconnections 68, 70, 82, 84 can be formed, for example, using a platedthrough-hole (PTH) conductive via process. Electrical connections 68,70, 82, 84 can be provided, for example, by a plating process using aconductive metal or metal alloy such as copper (Cu), gold (Au), nickel(Ni), tin-silver (SnAg), silver (Ag) or nickel-palladium (NiPd). Othermetals or metal alloys may be used in some implementations as well.Furthermore, in some implementations, some or all of the electricalconnections are provided on the outer surface of spacers, for example asa conductive coating or conductive tracks, conductive tape, orconductive glue.

The implementations of FIGS. 5 and 6 can reduce the overall footprint ofthe module. Modules 58, 76 can be made relatively small. For example, insome implementations, the modules have dimensions on the order of about3 mm or less (width)×2.5 mm or less (length)×3 or less mm (height). Forexample, in a particular implementation, the modules have dimensions onthe order of about 2 mm (width)×1.5 mm (length)×2 mm (height). Differentdimensions may be appropriate for other implementations. In addition,the implementation of FIG. 6 can reduce the amount of material needed tofabricate the module because only a single PCB substrate 72 is needed(rather than two PCB substrates 60, 62 as in the implementation of FIG.5).

FIGS. 7, 8 and 9 illustrate various modifications that can be made tomodule 20 of FIG. 1. For example, the module 86 of FIG. 7 includes anopening 30 in one of the spacer sidewalls 32 instead of in cover 28. Aspart of the fabrication of module 86, spacers 32 can be formed, forexample, by replication on PCB substrate 26 and cover 28. Providingopening 30 in one of spacer sidewalls 32 can be implemented in theembodiments of FIGS. 5 and 6, as well. In particular, opening 30 can beprovided in spacer 32.

FIG. 8 illustrates a module 88 that includes acoustics-enhancingfeatures 90 on inner surfaces of cover 28 and/or spacer sidewalls 32.Acoustics-enhancing features 90 can be shaped and sized to impact theacoustics or sound propagation in a pre-defined manner.Acoustics-enhancing features 90 on cover 28 can be formed, for example,by a replication or vacuum injection technique. Acoustics-enhancingfeatures 90 on spacers 32 can be formed, for example, by injectionmolding or by replication. The replication tool for making the coverwafer and spacer wafer can include provisions for forming theacoustics-enhancing features 90, which can be composed, for example, ofa polymer, foam or porous material. Acoustics-enhancing features 90 canbe implemented in the embodiments of FIGS. 5 and 6, as well. Inparticular, acoustics-enhancing features 90 can be provided on the innersurfaces of spacers 32 and/or cover 28.

FIG. 9 illustrates a module 92 that includes alignment or positioningfeatures 94 in the form of small projections that extend from the outersurface of cover 28. In the illustrated example, alignment features 94are located adjacent opening 30; however, in other implementations theymay be located elsewhere on the outer surface of cover 28. In someimplementations, a single projection surrounds opening 30 to formposition feature 94, whereas other implementations include multipleprojections. Features 94 can be used to facilitate positioning of theMEMS microphone module within the housing of an electronic or otherdevice. Alignment features 94 can be fabricated, for example, by areplication technique or by micromachining. Alignment features 90 can beimplemented in the embodiments of FIGS. 5, 6, 7 and 8 as well.

More than one of the various features of FIGS. 7-9 (i.e., an opening 30in a spacer sidewall 32; acoustics-enhancing features 90; and/oralignment features 94) can be incorporated into the same MEMS microphonemodule. Thus, the modifications illustrated in FIGS. 8, 9 and 10 can beused separately or in combination with the features of other modulesdescribed in this disclosure. The foregoing MEMS microphone modules canbe fabricated in a wafer-level process.

To improve the acoustics or sound propagation in the MEMS microphonemodules, polymer materials with mineral fillers and/or foam materialscan be used for one or more of the spacers 32, the internalacoustics-enhancing features 90 or the cover 28.

The foregoing MEMS microphone modules can be integrated with other smallmodules (e.g., a LED flash module, or sensors, such as ambient lightsensors) to help reduce the overall footprint of the modules evenfurther. For example, FIG. 10 illustrates an example of a module 100that combines the MEMS microphone module 58 of FIG. 5 with a LED flashmodule 101 to form a single integrated module in which MEMS microphonemodule 58 and LED flash module 101 are disposed side-by-side and sharespacers 32A, 64A in common. Spacers 32A, 64A serve as walls thatseparate the modules 58, 101 from one another.

In the illustrated example of FIG. 10, flash module 101 includes a LEDdevice 102 mounted on PCB substrate 62. Wiring 105 and electricalconnection 106 connect LED device 102 to a solder ball 29 on the outersurface of PCB substrate 62. Electrical connection 106 can be formed,for example, using a plated through-hole (PTH) conductive via process asdescribed above.

Although FIG. 10 shows a cover 28 having the same structure for the MEMSmicrophone portion and for LED flash portion, in some implementations,cover 28 can be structured differently for those portions. For example,cover 28 can incorporate a lens or diffuser for the LED flash portion.

Module 100 of FIG. 10 also can be fabricated, for example, in awafer-level process, an example of which is illustrated by FIGS. 11-15.As shown in FIG. 11, multiple ICs 22 and LED devices 102 are mounted ona first PCB substrate wafer 110, for example, by pick-and-placeequipment. ICs 22 and LED devices 102 are spaced from one another inview of the lateral dimensions of the modules.

As illustrated in FIG. 12, spacers 64, 64A and 104 are formed, forexample, by a replication or vacuum injection technique. In someimplementations, spacers 64 and 104 are formed as a single spacer, whichis diced vertically during subsequent processing (see FIG. 15). Spacers64, 64A can be replicated directly on first PCB substrate wafer 110 oron second PCB substrate 112, described below. Likewise, spacers 104 canbe replicated directly on first PCB substrate wafer 110 or on coverwafer 114, described below. Alternatively, the spacers can be providedby wafers that are glued or otherwise attached to PCB wafers 110, 112and cover wafer 114. The spacers can be composed of a polymer material,for example, a hardenable (e.g., curable) polymer material, such as anepoxy resin. In other implementations, the spacers are composed of a PCBmaterial (e.g., fiber glass or ceramic).

As illustrated in FIG. 13, MEMS microphone devices 24 are mounted on asecond PCB substrate wafer 112, which is attached over first PCBsubstrate 110 such that ICs 22 are housed in an area between first andsecond PCB substrates 110, 112. Spacers 64, 64A serve as sidewallssurrounding respective ICs 22. Second PCB substrate 112 has openingscorresponding to the area above each LED device 102.

As illustrated in FIG. 14, spacers 32, 32A also can be formed, forexample, by a replication or vacuum injection technique. Spacers 32, 32Acan be replicated directly on second PCB substrate wafer 112 or on coverwafer 114. The spacers can be composed of a polymer material, forexample, a hardenable (e.g., curable) polymer material, such as an epoxyresin. In other implementations, the spacers are composed of a PCBmaterial (e.g., fiber glass or ceramic).

As shown in FIG. 15, cover wafer 114 then is attached over second PCBsubstrate 112. Cover wafer 112 includes openings 48 each of whichcorresponds to opening 30 in FIG. 5. As explained above, openings 48 canbe formed, for example, by micromachining or by a replication technique,and can have a shape and size selected to achieve desired acoustics orsound propagation. In some implementations, cover wafer 114 hasdifferent sections composed of different materials that correspond tothe various functions of the combined module (e.g., a diffuser for theLED flash portion). The stack of wafers 110, 112, 114 then can beseparated (e.g., by dicing) into multiple modules similar to module 100in FIG. 10.

Exterior connections (e.g., solder balls or contact pads also can beprovided for the implementations of FIGS. 10-15 as described above. Inaddition, if a PCB spacer wafer is used to provide spacers 64, 64A,plated through-hole (PTH) conductive vias can be provided as describedabove.

FIG. 16 illustrates another wafer-level technique for fabricating module100 of FIG. 10. In this example, a first sub-stack 120 is formed byproviding spacers 64, 64A and spacer elements 104A on first PCBsubstrate wafer 110 (e.g., by replication (separate spacer wafer) orvacuum injection (replication directly on substrate)). Spacer elements104A correspond to roughly the bottom half of spacers 104 in FIG. 10. Inthis example, spacer elements 104A have about the same height as spacers64, 64A. In some implementations, spacers 64 and 104A are formed as asingle spacer, which is diced vertically during subsequent processing(see dicing line 124).

A second sub-stack 122 is formed by providing spacers 32, 32A and spacerelements 104B on cover wafer 114. Spacer elements 104B correspond toroughly the top half of spacers 104 in FIG. 10. In this example, spacerelements 104B are slightly longer than spacers 32, 32A (i.e., by anamount equal to the thickness of second substrate wafer 112. In someimplementations, spacers 32 and 104B are formed as a single spacer,which is diced vertically during subsequent processing (see dicing line124).

The various spacers and spacer elements in FIG. 16 can be formed, forexample, by replication directly on first substrate wafer 110 and coverwafer 114, or by providing a separate spacer wafer, as appropriate.

To complete the wafer stack, second substrate wafer 112 (with MEMSdevices 24 mounted thereon) is attached (e.g., by glue or some otheradhesive) to first sub-stack 120. In particular, the underside of secondsubstrate wafer 112 is attached to spacers 64, 64A, thereby forming anintermediate stack. Then, second sub-stack 122 is attached to theintermediate stack. In particular, spacer elements 104B of the secondsub-stack 122 are attached (e.g., by glue or some other adhesive) tocorresponding spacer elements 104A of the first sub-stack 120, andspacers 32, 32A are attached (e.g., by glue or some other adhesive) tothe upper side of second substrate wafer 112. The resulting wafer stack,which appears similar to FIG. 15, then can be separated (e.g., bydicing) into multiple modules similar to module 100 in FIG. 10. Exteriorconnections (e.g., solder balls or contact pads), as well as platedthrough-hole (PTH) conductive vias, also can be provided, for example,as described above.

FIGS. 17-18 illustrate yet a further wafer-level technique forfabricating MEMS microphone modules. In this example, a first sub-stack220 is formed by providing spacers elements 202A, 204A on first PCBsubstrate wafer 110. The spacer elements 204A have the same height asspacer elements 202A. A second sub-stack 222 is formed by providingspacer elements 202B, 204B on cover wafer 114 The spacer elements 204Bhave the same height as spacer elements 202B. The spacer elements inFIG. 17 can be formed, for example, by replication directly on firstsubstrate wafer 110 and cover wafer 114, or by providing separate spacerwafers. In addition to openings 30, the cover wafer 114 may includelenses or other beam shaping elements 210 at spaced intervals. When thewafers are stacked, each lens 210 is disposed over a respective one ofthe LED devices 102.

To form the wafer stack, a second substrate wafer 112 (with MEMS devices24 mounted thereon) is attached (e.g., by glue or some other adhesive)to first sub-stack 220. In particular, the underside of second substratewafer 112 is attached to spacers 202A, 204A, thereby forming anintermediate stack. Then, second sub-stack 222 is attached to theintermediate stack. In particular, spacer elements 202B, 204B of thesecond sub-stack 222 are attached (e.g., by glue or some other adhesive)to the MEM-side of the second substrate wafer 112, and spacers elements202A, 204A are attached (e.g., by glue or some other adhesive) to theopposite side of second substrate wafer 112. The resulting wafer stack(see FIG. 18) then can be separated (e.g., by dicing along lines 230)into multiple modules, one of which is shown in FIG. 19. Exteriorconnections (e.g., solder balls or contact pads), as well as platedthrough-hole (PTH) conductive vias, also can be provided, for example,as described above.

Although FIGS. 10-19 illustrate examples in which small MEMS microphonemodules are combined with flash LED modules, the MEMS microphone modulescan be combined with other small modules, including, for example,proximity sensor modules, time-of-flight (TOF) modules and cameramodules. Thus, LED flash module 101 of FIG. 10 can be replaced by one ofthese other types of modules in some implementations. By combining theMEMS microphone module with one or more other modules, the overallfootprint of the modules can be reduced, thereby allowing the modules tobe integrated into small consumer electronic or other products (e.g.,cellphones, laptops, headsets and media tablets, gaming applications,cameras, televisions and hearing aids) in which space is at premium.

Various modifications can be made within the scope of the invention.Accordingly, other implementations are within the scope of the claims.

What is claimed is:
 1. A module comprising: a MEMS microphone moduleincluding: a first substrate; a second substrate on which is mounted aMEMS microphone device, wherein the second substrate is separated fromthe first substrate by a first spacer; an integrated circuit devicemounted on the first substrate and arranged to perform processing ofsignals from the MEMS microphone device; and a cover separated from thesecond substrate by a second spacer; an opening in the cover or in thesecond spacer through which sound can enter; and a second module joinedto the MEMS microphone module, wherein the second module and the MEMSmicrophone module are side-by-side, and wherein interior regions of thesecond module and the MEMS microphone module are separated from oneanother by the first and second spacers.
 2. The module of claim 1wherein the MEMS microphone module and the second module share the firstsubstrate in common.
 3. The module of claim 2 further including anopto-electronic device mounted on the first substrate as part of thesecond module.
 4. The module of claim 1 wherein the MEMS microphonemodule and the second module share the cover in common.
 5. The module ofclaim 1 wherein the second module includes a third spacer that separatesthe first substrate from the cover.
 6. A MEMS microphone modulecomprising: a substrate; a MEMS microphone device mounted on a firstsurface of the substrate; an integrated circuit device mounted on asecond surface of the substrate, wherein the second surface is on anopposite side of the substrate from the first surface, the integratedcircuit device being arranged to perform processing of signals from theMEMS microphone device; and a cover separated from the substrate by afirst spacer; a second spacer on the second surface of the substrate;and an opening in the cover or in the first spacer through which soundcan enter.
 7. The MEMS microphone module of claim 6 includingacoustics-enhancing features on at least one of an inner surface of thefirst spacer or an inner surface of the cover.
 8. The MEMS microphonemodule of claim 7 wherein the acoustics-enhancing features are composedof a polymer material, a foam material or a porous material.
 9. The MEMSmicrophone module of claim 6 including one or more projections extendingfrom an exterior surface of the cover.
 10. The MEMS microphone module ofclaim 9 wherein the opening is in the cover and the one or moreprojections are located adjacent the opening.
 11. A wafer-level methodof fabricating a plurality of MEMS microphone modules, the methodcomprising: providing a first sub-stack that includes first spacerelements on a first side of a first substrate, the first side of thefirst substrate also including light emitting devices and integratedcircuits mounted thereon, wherein each light emitting device andintegrated circuit is surrounded laterally by respective ones of thespacer elements; attaching a second substrate to the first spacerelements, wherein MEMS microphone devices are mounted on a surface ofthe second substrate, the second substrate not extending over the lightemitting devices; providing a second sub-stack that includes secondspacer elements on a first side of a cover wafer; and attaching thesecond spacer elements of the second sub-stack to the surface of thesecond substrate on which the MEMS microphone devices are mounted. 12.The method of claim 11 wherein the first sub-stack, the second substrateand the second sub-stack form a stack, the method further includingseparating the stack into a plurality of modules, each of which includesa light emitting element, an integrated circuit and a MEMS microphonedevice.